[Devel] Re: [PATCH 1/2][INET] Fix potential kfree on vmalloc-ed area of request_sock_queue

[Eric Dumazet]

On Wed, 14 Nov 2007 21:08:29 +0300
Pavel Emelyanov <xemul at openvz.org> wrote:

> The request_sock_queue's listen_opt is either vmalloc-ed or
> kmalloc-ed depending on the number of table entries. Thus it 
> is expected to be handled properly on free, which is done in 
> the reqsk_queue_destroy().
> 
> However the error path in inet_csk_listen_start() calls 
> the lite version of reqsk_queue_destroy, called 
> __reqsk_queue_destroy, which calls the kfree unconditionally. 
> 
> Fix this and move the __reqsk_queue_destroy into a .c file as 
> it looks too big to be inline.
> 
> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
> 
> ---
> 

> +void __reqsk_queue_destroy(struct request_sock_queue *queue)
> +{
> +	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);

WARNING : lopt can be NULL here (or else the locking in reqsk_queue_yank_listen_sk() would be useless ?)

kfree(NULL) was ok, not NULL->nr_table_entries :)

> +	size_t lopt_size = sizeof(struct listen_sock) +
> +		lopt->nr_table_entries * sizeof(struct request_sock *);
> +
> +	if (lopt_size > PAGE_SIZE)
> +		vfree(lopt);
> +	else
> +		kfree(lopt);
> +}